Abstract: The explosive welded Al/Q235 joint was annealed under various heating time and temperature keeping the joint stay at solid state condition. The interfacial reaction layer feature was analyzed and the effects of heating temperature and time on the thickness of reaction layer were investigated, the growth of intermetallic compound at the joining interface was studied. The interfacial reaction layer consisting of Fe₂Al₅ adjacent to steel and Fe₄Al₁₃ adjacent to aluminum formed in the joining interface. The thickness of intermetallic compound increased with the longer of heating time. The results show that the growth of intermetallic compound satisfies the parabolic rule and that the growth active energy is 33.26 kJ/mol.